An outdoor unit of an air conditioner includes an inverter circuit for converting direct current (DC) power into three-phase alternating current (AC) power using a plurality of switching elements. Such an inverter circuit sequentially turns on and off the switching elements to generate three-phase AC power to drive a compressor motor and a cooling fan motor.
As for the switching elements, an increase in the output of the compressor motor increases the current flowing to the switching elements and thus increases the amount of heat generated in the switching elements. Thus, to prevent the switching elements from undergoing thermal breakdown, the air conditioner of Patent Literature 1 controls the rotational speed of the cooling fan using a temperature detection value detected by a thermistor and the value of current flowing through the compressor motor.